of westminster



A T. DAWSON AND G. T. BUCKHAM.

SIGHTING APPARATUS FOR ORDNANCE.

APPLICATION FILED NOV- ?l. 19H.

m mmm n w Z if d MI W w: W M RNN & 3 1 I A 6 0 3 1 ARTHUR TREVOR DAwsoN AND GEORGE LONDON, ENGLAND, AssIGNons 'ro ENGLAND.

SIGHTING APPARATUS roe ORDINANCE.

Specification of Letters Patent.

PATENT OFFICE.

THOMAS BUCKHAM, OF WESTMINSTER,

VICKERS LIMITED, OF WESTMINSTER,

Patented June 10, 1919.

Origihal application .filed June 22, 1915, Serial No. 35,729. Divided and this application filed November 27,

T 0 all whom it may concern:

Be it known that we, Sir ARTHUR T. DAwsoN, knight, and GEORGE T. BUCKHAM, both subjects of the King of Great Britain, residin at and whose post-oflice addresses are VlclCeIs House, Broadway, Westminster, in the county of London, England, have, invented certain new and useful Improve ments in or Relating to Sighting Apparatus for Ordnance; and we hereby declare the following to be a full, clear, and exact description of the invention, such as will en able others skilled in the art to which itappertains to make and use the same.

Inconnection with ordnance sighting apparatus, it is usual to provide means where by, when the trunnions of a gun are inclined to the horizontal as a resultof the gun carriage resting on uneven ground, the sight will be deflected to compensate for the lateral error which would otherwise occur. In addition to this error there is however a further error which as is Well understood affects the layingof the gun for range, this error resulting from the fact that the angle between the aXis of the gun and the sight line-i. e. the angle of tangent elevation when projected on to a vertical plane is less when the trunnion axis is inclined than when it is level. and therefore less than the angle corresponding to the range registered on the range dial or its equivalent, and the chief object of the present invention is to devise improved means for correcting this error.

According to this invention we provide means for automatically correcting the angle of tangent elevation by varying the reading of the range indicating device, the amount of such correction being dependent upon the inclination of the gun trunnions and the range of the object.

For this purpose we may provide means whereby the adjustment of a spirit level or other gravity controlled device to its zero position moves a cam into such a position that when the gun is being elevated for range the cam eiiects relative movement between the range dial and its pointer.

In order that the said invention may be clearly understood and readily carried into effect we will describe the same more fully Serial No. 63,890.

with reference to the accompanying draw: ings, in which Figures 1, 2 and 3 are respectively a side elevation a plan and a sectional rear elevation showing in a more or less diagrammatic manner a constructional form of the invention for effecting relative movement between the range dial and its pointer, and

Fig. 4 is a section taken approximately on the line 1, 1 ofFi'g. 1.

A is one of the un trunnions and B represents theaforesaid cam,

E represents the aforesaid spirit level by the adjustment of which the cam B is moved into such a position that during the elevation of the gun for range the said cam will effect relative movement between the ran e dial F and its pointer F. This level, in tEB example shown, is constituted by a liquid and bubble containing tube mounted in a casing which is pivotally mounted on a bracket G carried by the sight arm which moves during pointing only. The bubble is a handwheel E actuating a worm sector 6 on the casing of the bubble containing tube. This worm also gears with a worm wheel sector formed on one arm of a rocking lever E so as to impart thereto an angular movement proportional to the inclination of the trunnions. The rocking lever carries a roller 6 engaging in a slot b on the rear surface of a link having a slot B (constituting the aforesaid cam) which when the link is in its normal position is concentric with the trunnion axis. This link is pivoted at b to the bracket G. The slot B receives a roller f on the end of the range pointer F which is rotatably mounted on the boss of the range dial F. The dial and pointer are carried on the cradle. In the normal position (i. e. for level ground) the roller 1" moves in the slot B without alfecting the position of the pointer F during the elevation of the gun for range, since as above stated the slot B is, in this condition of affairs, concentric with the gun trunnions. When, however, the bubble E is brought to its zero position to correct for sloping ground the slotted link B is rocked about its pivot b by the roller 6 and the slot 1) and the slot B no longer remain concentric with the trunnion axis so that as the gun is being elevated for range the slot B imparts movement to the pointer F proportional to the angle of inclination of the trunnions and to the range. By adjusting the range dial to maintain the desired graduation opposite the pointer the necessary correction is imparted to the angle of tangent elevation.

What we claim and desire to secure by Letters Patent of the United States is 1. In ordnance sighting apparatus, the combination with the range indicating device, of a slotted member, a projection connected to the range indicating device and em gaging said slotted member, means for adusting said slotted member in accordance with the degree of inclination of the gun trunnions, and means for effecting relative movement between said slotted member, and projection in accordance with the range of the target.

2. In ordnance sighting apparatus, the combination with the members of a range indicating device, of a slotted member, a projection connected to one member of the range indicating device and engaging said slotted member, means for adjusting said slotted member in accordance with the degree of inclination of the gun trunnions, and means for efi'ective relative movement be tween said slotted member and projection in accordance with the range of the target;

3. In ordnance si htin apparatus of the kind having an in izpen ent line of sight, the combination with the range indicating device carried by the gun cradle, of a mem ber moving only during the pointing of the gun, an arm pivoted to said member and formed with a slot which is normally c'oncentric With the axis about which said member moves, a projection. connected to the range indicatin device and engaging in said slot so that re 'ative movement occurs be tween the slot and the projection durin the ranging of the gun, and means for ad usting'said slotted arm in accordance with the degree of inciinati'on of the gun trunnions. In ordnance sighting apparatus having an independent line of sight, the combination. with the members of the range indicating device carried by the gun cradle, of a sight'arm moving only during the pointing of the gun, a slotted member pivoted to said sight arm with its slot normally concentric with the axis about which said sight arm moves, a projection connected to one memberof the range indicating device and engaging said slotted member so that relative movement occurs between the slotted memher and the projection during the ranging of the gun, and means for adjusting said slotted member in accordance with the degree of inclination of the gun trunnions.

In testimony whereof we afiix our signatures in the presence of two witnesses.

ARTHUR TREVOR DAWSON. GEORGE THOMAS BUCKHAM.

Witnesses:

Jim. R. CAswnLL, GLADYS M. BARDEN.

Copies of this patent may be obtained for five cents each, by addressing the "Commissioner of Patents, Washington, D. 6.

Correction in Letters Patent No. 1,306,413.

It is hereby certified that in Letters Patent. No. 1,306,413, granted June 10,

1919, upon the application of Arthur Trevor Dawson and George Thomas Buckham, of Westininster, London, England, for an improvement in Sighting Apparatus for Ordnance, an error appears in the printed specification requiring correction as follows: Page 2, line 31, claim 2, for the word effective read ejfecting;

and that the said Letters Patent should be read with this correction that the same i may conform to the record of the case in the Patent Oflice.

Signed and sealed this 1st day of July, A. D., 1919.

J. T. NEWTON,

Commissioner of Patents.

[SEAL] 

